Simultaneous measurement of liquid level and temperature employing a single uniform FBG

Abstract

We report a novel liquid level sensor based on a simple uniform fiber Bragg grating by monitoring both the short-wavelength-loss peaks and its Bragg resonance. The liquid level can be measured from the amplitude changes of the short-wavelength-loss peaks, while temperature can be measured from the wavelength shift of the Bragg resonance. Such a scheme has some advantages including robustness, simplicity, flexibility in choosing sensitivity, and simultaneous temperature measurement capability.